Many vehicles need the capability for the addition or the removal of passenger seats and/or cargo. In addition, such vehicles also need the capability to easily relocate or reposition seats and/or cargo. This is particularly true in connection with aircraft where it is frequently necessary to change the spacing between seats to increase or decrease the passenger density throughout a portion or the entire aircraft. This would be the case where it was desired to change the density of loading of a particular aircraft from its normal first class and tourist density of loading configuration to an all economy or tourist configuration which might be the case in connection with charter operations. In addition, some flights, especially those that are scheduled late at night, may be reconfigured to handle both cargo and passengers in the compartment that is normally reserved for only passenger seats.
To provide this capability the manufacturers of aircraft and other vehicles have installed locking tracks that run lengthwise in the floor of the major compartment of the aircraft. These locking tracks commonly have a slot that runs the entire length of the track which is located on the upper surface of the locking track. Semicircular cut-out portions that extend outward from this slot are located at equally spaced distances along the locking track. The purpose of the slot and the cut-out portions is to receive portions of various types of track fasteners to permit the track fasteners to be positioned along and locked to the track in order to secure passenger seats and/or cargo that is associated with the track fasteners to the locking tracks. In this manner passenger seats and/or cargo can be attached to and removed from the vehicle, or, if necessary, the passenger seats and/or cargo can be repositioned within the vehicle.
Any track fastener that is designed to cooperate with a locking track must be designed in a manner so that safety is the primary consideration. This is particularly true in connection with aircraft since a passenger seat that was not securely fastened to the locking track could easily cause injury to the occupant of the seat or to other occupants of the aircraft. Even in the case involving cargo located in the aircraft, it is necessary from a safety standpoint to insure that the cargo does not come loose since loose cargo could injure occupants of the aircraft and/or cause structual damage to the aircraft that could result in serious injury or the loss of life. From a safety standpoint any track fastener must have the ability to safely distribute the load to the track so that an unsafe load is not transmitted through only a few load distribution points in a manner that could cause an unsafe condition. It is also desirable for any track fastener to provide an indication of when the track fastener is properly locked to the locking track so that the person that is inspecting or installing the track fastener can readily determine if the track fastener is properly locked to the track. Without such an indication, the possibility of a fastener not being properly locked to the track would greatly increase, and this would have an adverse effect upon the safe operation of the vehicle.
From a practical standpoint any track fastener should be capable of being easily installed on and removed from the locking track so that passenger seats and/or cargo can easily be installed in and/or removed from a vehicle with a minimal amount of time and effort. Also since passenger seats and/or cargo may need to be shifted within a vehicle without removing the seats or cargo from the vehicle it is desirable to have track fasteners that will easily permit the moving or shifting of such seats and/or cargo.
In the past, attempts have been made to provide the features and capabilities that have been previously mentioned as being desirable in a track fastener. One such attempt is illustrated by the track fastener that is set forth in U.S. Pat. No. 3,847,344. The track fastener disclosed in this patent attempts to provide apparatus for indicating when it is properly secured to the locking track. This is accomplished by means of a locking wire that can be pivoted into position after the fastener has been placed in its locked position. However, the locking track fastener in this patent requires a separate distinct step in order to properly position the locking wire, and, in addition, the locking wire may be rotated into its partially locked position, and, hence, convey the impression to an observer that the locking fastener is in its locked position when in fact it is not. In addition, the track fastener set forth in this patent has portions that engage the track that do not permit the track fastener to be readily moved lengthwise along the track since these portions must be removed from the semicircular cut-out portion in the track. Consequently, even though the track fastener described in this patent has some provision for indicating when the fastener is locked to the track, the track fastener may also convey a false impression that it is locked. In addition, this track fastener is not as easy to install and remove from the track as would be desirable and it is not capable of being moved from one position on the track to another without removing it from the track.
Present invention overcomes these disadvantages and provides a track fastener that is easy to install and remove from a locking track that provides a positive indication when the track fastener is in its locked position. This track fastener also is capable of being moved along the length of the locking track without removing it from the track and consequently a seat or cargo that is attached to the fastener can easily be moved about within a vehicle without the necessity of lifting the seat or the cargo.